Foundation Design and Construction over a Waste Filled Limestone Quarry: Fid-Bau Portal

Foundation Design and Construction over a Waste Filled Limestone Quarry

Gallagher, Marc J. / Langan, Bernard F.

This paper discusses the challenges encountered during construction of the foundation system for a large retail store in the northwest suburbs of Philadelphia, Pennsylvania. The original shallow foundation design plan had to be abandoned when a deep, historic limestone quarry, filled with miscellaneous fill material including construction debris, municipal waste and organic material, was encountered within a portion of the building footprint during excavation. Following a subsurface investigation program (utilizing SPT, CPT and rock probes) and research into feasible foundation solutions, an alternative foundation system consisting of grade beams supported on drilled mini-piles in the quarry portion of the building, and strip footings in the non-quarry portion of the building was selected. Further complicating foundation design was the highly pinnacled, sinkhole susceptible, limestone and dolomite bedrock underlying the site. Installation of the mini-piles was performed through difficult subsurface conditions — along the former quarry face, through waste material, and into limestone rock with pinnacles and voids — pushing the contractor and their equipment's capabilities. This paper highlights the site history, subsurface investigation, foundation design, and construction issues.